URBA is the largest union of Argentina, with 76 clubs directly affiliated and 15 competing as guests.

[5] In 1951, the change of name to Spanish "Unión Argentina de Rugby", was after a request by the Argentine Olympic committee and it continued at the same time to work as local federation of Buenos Aires clubs, and national federation, recognized by International Rugby Board.

As a result of a restructuring of the Argentine rugby in 1995, the "Unión de Rugby de Buenos Aires" was created with the purpose of organising competitions in the city district and nearest towns like San Isidro and La Plata, while the remaining part of the Buenos Aires Province (including populous cities like Mar del Plata or Tandil) remained under other provincial unions.

Therefore, the RPRU championship was renamed "Torneo de la URBA" and continued with the same format, while the Argentine Union (UAR) took over national teams only.

The first division is the Top 12, contested by 12 clubs of the Buenos Aires area and also the oldest rugby competition in Argentina, with its first edition held in 1899.